If your copy of XP is found to be pirated, the software will turn your back ground to black each time you log on. Users will be able to replace the desktop wallpaper they desire but the black screen will reappear every 60 minutes, before another blackout occurs. I guess there's no point of changing the background back to your favorite picture.
The other feature is Microsoft puts a translucent banner at the bottom of the screen informing the user that the copy of Windows is not genuine. Apparently, that’s just the start of Microsoft’s nagging until the users buy a legitimate copy.
Anybody who pirates this software is probably smart enough to get around this by turning off the automatic updates.
SOURCE : TheStar